当前位置： SCI文献检索 > JOURNAL OF CELLULAR PHYSIOLOGY期刊下所有文献 > Calcium transport by sarcoplasmic reticulum of vascular smooth muscle: II. Effects of calmodulin and calmodulin inhibitors.

Calcium transport by sarcoplasmic reticulum of vascular smooth muscle: II. Effects of calmodulin and calmodulin inhibitors.

Abstract：

:The role of calmodulin (CaM) in modulating calcium (Ca) uptake by sarcoplasmic reticulum (SR) of vascular smooth muscle was studied in saponin skinned strips of rat caudal artery. Exogenous CaM concentrations ranging from 0.3-1.8 microM did not statistically change the steady state MgATP-dependent Ca content, the MgATP-independent Ca content, or the oxalate-stimulated Ca influx. Calmidazolium (CDZ), W-7, and trifluoperazine (TFP) were used to examine the potential effect of an endogenous CaM pool on inward Ca transport. The IC50 of these antagonists for inhibition of Ca-CaM-stimulated phosphodiesterase activity and Ca-activated superprecipitation of canine aortic actomyosin was measured and found to be in the low micromolar range with a rank order of potency for inhibition of CDZ greater than TFP greater than W-7. In skinned tissues, micromolar concentrations of antagonists that inhibited CaM-mediated reactions in isolated enzyme systems did not reduce Ca content or oxalate-stimulated Ca influx. At higher concentrations of 100-200 microM, the MgATP-dependent Ca content was significantly reduced by TFP and W-7 but not by CDZ. The order of potency for inhibition of Ca uptake was TFP greater than W-7 greater than CDZ. The MgATP-independent Ca content was significantly decreased only by 200 microM TFP. Although none of these inhibitors significantly altered Ca efflux at concentrations up to 100 microM, Ca release was significantly stimulated by all three at 200 microM. The TFP-stimulated Ca release was partially inhibited by ruthenium red. The results indicate that neither exogenous CaM nor an endogenous CaM pool directly modulates inward Ca transport by the SR of saponin skinned caudal artery. The inhibition of Ca uptake produced by hundred micromolar concentrations of CaM antagonists fails to correlate with the order of and with the potency of inhibition measured in isolated enzyme systems. This suggests that the inhibition of Ca uptake produced by high concentrations of these antagonists may be independent of a specific interaction with CaM. The activation of Ca release by high concentrations of CaM antagonists may involve a nonspecific increase in membrane permeability as well as modulation of a membrane Ca channel.

journal_name

J Cell Physiol

journal_title

Journal of cellular physiology

authors

Stout MA,Silver PJ

doi

10.1002/jcp.1041530121

keywords:

subject

Has Abstract

pub_date

1992-10-01 00:00:00

pages

169-75

issue

eissn

0021-9541

issn

1097-4652

journal_volume

153

pub_type

杂志文章

在线工具

Calcium transport by sarcoplasmic reticulum of vascular smooth muscle: II. Effects of calmodulin and calmodulin inhibitors.